The Pentagon has said its entire fleet of F-35 fighter jets could resume flying after being grounded last week following the discovery of a cracked engine.

Late week, the Pentagon announced that it had suspended all 51 of its F-35 warplanes after an inspection revealed a crack on a turbine blade in a test aircraft's engine at the Edwards Air Force Base in California.

"F-35 flight operations have been cleared to resume," Pentagon spokeswoman Kyra Hawn said on Thursday, explaining that no additional cracks were found during inspections of the rest of the fleet or in any spare engines.

The suspension marked the second engine-related grounding in two months of the F-35 Joint Strike Fighter programme, the Pentagon's largest weapons programme with an estimated cost of almost $400bn.

The Marines Corps version of the plane was grounded for nearly a month starting in mid-January because of a faulty hose in the engine.

The warplanes have stealth capabilities and a top speed of 1,930km/h.

A US watchdog group, the Project on Government Oversight, said the programme's performance is disappointing amid concerns from some Congress members about the high price.

"The F-35 is a huge problem because of its growing, already unaffordable, cost and its gigantically disappointing performance," the group's Winslow Wheeler said.

"That performance would be unacceptable even if the aircraft met its far-too-modest requirements, but it is not."

Source: Agencies